Very interesting. It does seem a bit suspicious on the one hand. On the other hand, you have to ask yourself what exactly was he trying to accomplish with his actions. He may have been trying to see your reaction to the Ace before declaring his intention. Or perhaps thinking that his hand might be good, he wanted to see if you would muck your hand, in which case he could say that he meant to call, but if you turned over better he could say that he hadn't called, which he hadn't.
It was smart of you not to react and to ask him before you did anything. A lot of people would have made an assumption and then acted upon that assumption, leaving it up to someone else to interpret his intention and determine whether his hand was still live or not if, for instance, you thought that he was folding and then mucked your hand.